To support the win condition of your main engine, you'll need speed ramp (Haste and Charge) and crowd control (Freeze and Slow). Here are some example options, but you can usually swap in other items and skills that fulfill similar roles.
Speed Ramp
Metronome
Since it doesn't have a wind-up time, the Metronome is an awesome catalyst to funnel your Atomic Clock's 1.0 second cast into.
In this build, we use Soldering Gun. While the Burn does help (it was 7 Burn, the final screen screenshot is bugged), the main purpose here is as a Multicast activator.
Soldering Gun
So in 1.0 second, the Atomic Clock bounces through the Metronome which accelerates the Soldering Gun into a Multicast which bounces back into the Atomic Clock.
Fiber Optics
Fiber Optics (placed leftmost) allows your Atomic Clock to ramp up two items at once, the Metronome and your damage source (placed rightmost).
What's great about Fiber Optics itself is that it can trigger from anywhere on your board, so it gives you the flexibility to move things and trigger more adjacent effects.
Tools of the Trade
Although Tools of the Trade seems ideal in a composition with many Tools, you can still get a lot of value out of it if you have one Tool that casts very fast. In this example's case, it's Smoldering Gun and Chris Army Knife.
Chris Army Knife is one of Dooley's best items in general right now since he's versatile - he can help support builds as a Friend, Weapon, and/or Tool.
Knife Tricks
If you can find it, Knife Tricks helps your engine ramp up in longer fights.
Crowd Control
While you speed up your own build, you can support your build by also slowing down your enemy's build.
Pierre's 5.0 second cast is very slow but the main part you want is its second effect, "When you use the Core, Freeze an item."
This gives your Core, which will already be casting quickly a way to also offer crowd control.
You can also look for skills like Sabotage and Stop That! to help disrupt your opponents.